An anal fissure is a cut or tear in the lining of the anus. The anus is the opening through which stool leaves the body. Tears generally occur just inside the opening.
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The exact cause of an anal fissure is unknown. In most cases, tearing is the result of trauma to the anal lining. Trauma can be caused by:
- A large, dry, or hard stool
- Frequent diarrhea
- Tightened anal sphincter, a group of muscles that open and close the anus
- Anal irritation
Last reviewedNovember 2013by Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.